Siloxanes are commonly included in contact lenses to improve their oxygen permeability. However, the inclusion of siloxanes can have a detrimental effect on the wettability or hydrophilicity of the lens. One suitable approach to overcome this issue is to coat or modify the contact lens surface, preferably with a biocompatible material.
Oxygen permeability of hydrophilic contact lens formulations can be improved, for example, by adding various silicon- and fluorine-containing hydrophobic monomers. Such modifications, however, may come at the expense of lens wettability and biocompatibility; for instance, materials exhibiting high gas permeabilities due to the inclusion of high levels of silicon or other strongly hydrophobic monomers frequently exhibit reduced wetting characteristics. This can lead to various problems ranging from poor lens movement on the eye, increased fouling due to lipid, protein, and/or biomolecule adherence to the lens surface, and adhesion of the lens to the eye. These and other issues can be remedied by providing a surface modification that makes the lens surface considerably more wettable.
Various techniques for improving the hydrophilicity of contact lenses have been disclosed, many of which involve a plasma treatment step. It would be desirable to have a surface modification process that did not require a separate plasma unit operation, as these techniques can be highly variable, costly, and inconvenient.
In general, various surface properties of materials, such as bioactivity, chemical reactivity, gas permeability, and wettability, can be improved by polymeric surface modifications. Other desirable features that can be enhanced or improved by surface modifications include adhesion, biocompatibility, liquid or stain resistance, lubricity, protein resistance, anti-reflective behavior, selective binding of biomolecules, and wear resistance. Although some methods of surface modification of polymers are known, it would be useful to provide improved surface modifications and processes for preparing the same.